I have not tried to copy and edit the Sales Order report. The problem is that I am making a "Sales Order," but our Sales Order is more like a Statement of Services or a Work Order, and not a Sales Order like the report which exists. However, the Sales Order (Custom) report can be illustrative. In your report, the DetailReport with SalesOrderLine is the last thing on the report (other than the footer. It appears that when you instert a Detail Report, you effectlively end the Main Detail because you cannot have fields on the Main Detail which fall after the Detail Report.
Here is a diagram of what I am trying to accomplish (tables and relationships are on left, structure or report is on the right). My Table has three sub-tables. One is a Text field, two are Dropdowns (not that this matters). This allows a user to enter any number of Summary Lines. For example, we may want to enter:
1. Rush order, deliver by MM/DD/YYYY
2. Must ship via FedEx, no UPS
3. Deliver data on encrypted DVD
These entries may number 10 or 20 possibly.
Likewise the two tables that hold which metadata fields are being delivered. Each project might require delivery of one, two, or up to twenty metadata fields. These fields are stored in another table.
As you can see from the diagram, I need to enter data on the Main Detail which will display after I insert my first Detail Report. Then I will insert a few more Detail Reports, and then I want to continue to insert data on the Main Detail.